Coplaner LED array and driver assembly

Abstract

An LED array and driver design minimizes space requirements and simplifies assembly, while reducing costs. A printed circuit board with LED driver electronics has a central opening through which the LED array is mounted. In one form the LED array is a chip on board (COB) array, the array being circular and fitting closely within the central opening of the PCB. Four integral leaf springs are formed into the flat PCB, in position to push the LED array down when the PCB and LED array are attached against the heat sink. Two of the springs have electrical contacts that make contact with those of the LED array. With the LED array and driver circuit on the face of a light assembly, the space rear of the driver circuit is free to be open to air flow for cooling.

We claim: 
     
       1. In an LED light assembly, an LED array mounted in a space efficient manner against a heat sink, the assembly comprising: an LED array on a heat conducting substrate, a printed circuit board (PCB) with a central opening sized to receive the LED array, the PCB having pairs of slits extending into the board from the central opening, so as to form a plurality of cantilevered spring arms in the board, some of the spring arms including PCB electrical contacts positioned to press down against the LED's heat conducting substrate when the LED array is assembled against the back side of the printed circuit board, and the heat conducting substrate of the LED array having mating LED electrical contacts in position to be engaged with the PCB electrical contacts, a heat sink plate assembled behind the LED array such that a back side of the heat conducting substrate of the LED array is pressed against the heat sink plate, and the printed circuit board being secured to the heat sink plate by fasteners such that the spring arms are deflected and push down on the heat conducting substrate of the LED array, to make both electrical contact with the LED array and heat transfer contact of the LED heat conducting substrate with the heat sink plate, thereby providing a compact, efficient retention assembly for the LED array. 
     
     
       2. The portable light assembly of  claim 1 , including four said spring arms at generally even spacing around the central opening. 
     
     
       3. The portable light assembly of  claim 2 , wherein the central opening, and the LED array, are circular. 
     
     
       4. The portable light assembly of  claim 1 , wherein the LED array is a COB array. 
     
     
       5. The portable light assembly of  claim 1 , wherein the back side of the printed circuit board is routed to form a shallow recess around the central opening, the central opening being round, the recess having a plurality of expanded corners, and the conducting substrate of the LED array having a plurality of corners, each of which lies against an expanded corner of the recess, two of the corners of the LED's heat conducting substrate having said mating LED electrical contacts, and the PC board bearing against the LED's heat conducting substrate only at said corners of the heat conducting substrate and of the recess, where the spring arms are located on the PC board. 
     
     
       6. The portable light assembly of  claim 5 , wherein two opposed ones of said spring arms include said PCB electrical contacts, and two further spring arms bear against the heat conducting substrate solely to press the heat conducting substrate against the heat sink plate for heat transfer. 
     
     
       7. The portable light assembly of  claim 1 , wherein said fasteners are machine screws engaged in threaded holes of the heat sink plate. 
     
     
       8. The portable light assembly of  claim 1 , wherein the PCB is of the material FR4. 
     
     
       9. The portable light assembly of  claim 1 , wherein the heat conducting substrate of the LED array is ceramic. 
     
     
       10. The portable light assembly of  claim 1 , wherein the printed circuit board has on at least one surface LED driver electronics for the LED array, connected to the PCB electrical contacts. 
     
     
       11. In a portable light assembly, a circular LED array mounted in a space efficient manner against a heat sink, the assembly comprising: a circular LED array in a tight cluster, on a heat conducting substrate, a printed circuit board annular in shape and with a central opening sized to receive the circular LED array, the printed circuit board having on at least one surface LED driver electronics, the annular PCB having pairs of slits extending into the board from the central opening, so as to form a plurality of cantilevered spring arms in the board, some of the spring arms including PCB electrical contacts positioned to press down against the LED's heat conducting substrate when the LED array is assembled against the back side of the printed circuit board, and the heat conducting substrate of the LED array having mating LED electrical contacts in position to be engaged with the PCB electrical contacts, a heat sink plate assembled behind the LED array such that a back side of the heat conducting substrate of the LED array is pressed against the heat sink plate, and the annular printed circuit board being secured to the heat sink plate by fasteners such that the spring arms are deflected and push down on the heat conducting substrate of the LED array, to make both electrical contact with the LED array and heat transfer contact of the LED heat conducting substrate with the heat sink plate, whereby the LED driver electronics are essentially coplanar with the LED array, providing a compact assembly and avoiding a need for a special LED holder.